1, the tire opening is not straight, exhaust and re-inflate, and if necessary, touch the tire opening with detergent or soapy water.
2. Check whether there is any problem with the rear shock absorption, whether there is any problem with the rear bearing and whether the scales on both sides are symmetrical.
3. The left and right sprocket adjusters have different scales. A front shock absorber failed. With the use of the car (uphill or overloaded), the rear wheel is dragged forward by the chain. Because the chain has only one side, the stress on both sides of the rear wheel is uneven, which makes the rear wheel of the car run off.